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Plume | Attackathon

53035 sc medium share lock applied to wrapper instead of end user breaks transfers or bypasses lock

Submitted on Aug 14th 2025 at 17:48:31 UTC by @Afriauditor for Attackathon | Plume Network

Description

Brief / Intro

The vault’s share lock mechanism is applied to the wrapper contract’s address rather than the actual end user in both the bridge (depositAndBridge) and non-bridge (depositOneInch) deposit flows. Depending on configuration this causes one of two critical outcomes:

  • If the vault enforces the BeforeTransferHook, immediate post-deposit transfers revert (flows break).
  • If the hook is disabled, users receive transferable shares instantly, effectively bypassing the intended lock.

Either outcome undermines the intended security model and can brick core functionality.

Vulnerability Details

When the wrapper calls into the teller (TellerWithMultiAssetSupport) it is the wrapper that is msg.sender. This results in:

  • Shares minted to the wrapper
  • The share lock recorded against the wrapper's address rather than the end-user

Example behavior in the teller called by DexAggregatorWrapperWithPredicateProxy:

// shares minted to msg.sender (the wrapper)
shares = _erc20Deposit(depositAsset, depositAmount, minimumMint, msg.sender);

// lock recorded for msg.sender (the wrapper), not the user
_afterPublicDeposit(msg.sender, depositAsset, depositAmount, shares, shareLockPeriod);

Consequences:

  • If the vault enforces BeforeTransferHook, any immediate transfer from the wrapper (to the user or onward into the bridge flow) invokes beforeTransfer(wrapper) and triggers: if (shareUnlockTime[from] > block.timestamp) revert SharesAreLocked(); — causing the transfer to revert.
  • If the hook is disabled, the user receives transferable shares immediately (lock bypassed).

Impact Details

All wrapper-based deposit paths (both depositOneInch and depositAndBridge) are blocked when the vault enforces BeforeTransferHook, because moving the freshly minted shares out of the wrapper immediately triggers SharesAreLocked. If the hook is not enforced, the intended share lock is effectively bypassed and users obtain transferable shares immediately, breaking invariants.

Proof of Concept

Setup

  • Configure the vault to invoke BeforeTransferHook.beforeTransfer(from) on every transfer.
  • Set shareLockPeriod = 2 days in the teller.

Trigger

  • Call either depositOneInch (non-bridge) or depositAndBridge (bridge) via the wrapper.

Observed behavior

  • Inside the teller, shares are minted to the wrapper; _afterPublicDeposit sets shareUnlockTime[wrapper] = now + 2 days.
  • The wrapper immediately attempts to move those shares (to the user or into the bridge flow).
  • Vault calls beforeTransfer(wrapper) → sees lock active → reverts with SharesAreLocked.

Minimal reproduction summary

  • Wrapper calls teller deposit path.
  • Teller treats wrapper as msg.sender, mints shares to wrapper and records lock against wrapper.
  • Immediate transfer from wrapper hits BeforeTransferHook and reverts due to lock.

References